The processing and handling of paper sheets to form documents consumes an enormous amount of human and financial resources, for large as well as small organizations. In view of the above, various paper-handling machines have been developed. In known paper-handling machines that separate and transport individual pieces of paper from a stack of paper sheets, the stack of paper sheets is first loaded onto some type of conveying system for subsequent processing. The stack of paper sheets is advanced as a stack or by individual paper sheets in the stack.
In such a paper-handling machine, the various forces acting on the sheets of paper in advancing the stack downstream often act counterproductively relative to each other. For example, inter-sheets of paper stack forces exist between each of the sheets of paper that are in contact with each other in the stack. These inter- sheets of paper forces created by the stack advance mechanism, the frictional forces between the sheets of paper, and electrostatic forces that may exist between sheets of paper, tend to oppose the force required to shear the lead sheet of paper from the stack.
A condition called shingling occurs with paper feeders where the leading edge of one piece of media slips under the trailing edge of the media before it is in a feeder queue. When this occurs, the leading edge of the second piece of media is masked from detection by the feeder sensor, and the feeder monitoring module is likely to miscount the number of pieces of media or paper fed. This, in turn, may lead to loss of synchronization with the printing control module that expects to match a different print page with each and every piece of media fed.
The prior art has attempted to solve the shingling problem by reporting the shingling as an error to the customer. Other prior art solutions simply let the shingled sheet of paper glide through the system without being printed on. In these cases, there is a definite loss of throughput, as well as blank pages in the print stream. Certain less robust systems could actually result in wrong information being printed on the shingled piece.